The role of decreased renal artery perfusion pressure in redistribution of renal cortical blood flow during acute hemorrhagic hypotension is unclear. Renal artery hypotension was produced in intact dogs by an intra-aortic balloon catheter placed cephalad to the origins of the renal arteries. Renal cortical perfusion was assessed using selective renal magnification arteriography, isotopically labeled microspheres, and xenon-133 washout. After 60 minutes of decreased renal artery perfusion pressure (40 to 50 mm Hg), no changes were noted in renal cortical perfusion arteriographically. Microsphere distribution to each cortical zone was unchanged, despite a marked decrease in total renal blood flow and in flow to each zone.I33Xe washout curves permitted two interpretations: Either redistribution of blood flow away from the cortex occurred, or parallel decrease in flow to each zone occurred without redistribution. Results indicate decreased renal artery perfusion pressure does not cause redistribution of renal cortical blood flow in our model.
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